Multi-graded lubricant for 2-cycle engines



United Smtes Patent G 3,015,320 MUL GRADED LUBRICANT FOR Z-CY'CLE ENGENES Elmer W. Brennan, Carpentersville, and James G. Hail, Woodstock, 111., assigners to The Pure Gil Company, Chicago, Ill., a corporation of (ihio No Drawing. Filed Jan. 5, 1956, Ser. No. 557,434 Claims. (Cl. 123-1) This invention relates to the lubrication of Z-cycle, spark-ignited, internal combustion engines. It is more specifically concerned with an additive-containing lubricating oil which may be advantageously employed in the lubrication of this type of engine.

Because of the substantial increase in the use of 2- cycle engines for power lawn mowers and other garden implements, portable equipment, such as chain saws, pumps, electrical generators, etc., as well as marine outboard engines, by the general public, satisfactory, troublefree engine performance without constant attention by trained engine-service personnel is a desideratum of operators of such engines. Two-cycle engines giving dependable performance can be manufactured in small designs, making their use eminent for these services. Engines of this type are distinguished by the use of a lubricating oil-gasoline motor fuel mixture which not only functions as a fuel, but also provides lubrication in a highly diluted form without the sump-type of lubrication system. Even under a wide variety of conditions, these engines function with little difiiculty or trouble. Operating difficulties encountered which are attributable to the fuel-lubricant mixture are due to spark plug fouling, ring sticking, excess combustion chamber deposits, etc. Because these troubles can result from the characteristics of the oil employed in the fuel-lubricant mixture, engine manufacturers warn against the use of lubricating oils containing additives. Although additive treatment of lubricating oils employed in many automotive engines of the 4-cycle type is beneficial, generally this practice has been unsatisfactory for formulating oil to be used in fuel mixtures for 2-cycle engines. In considering the operation of 2-cycle engines and the effect of oil in the combustion process, it would appear that straight mineral oils containing no additives will, in general, provide the most suitable engine performance. If additives are to be employed, lubricating oil formulators have believed that particular care should be taken to eschew the use of additives having ash-forming tendencies to avoid accumulation of deposits. However, contrary to the general recommendations of the prior art,

there has been developed an ash-forming, additive-con- H taining lubricant which may be employed in the formulation of lubricant-motor ing additive. These and other objects will become more apparent from the following detailed description of this invention.

According to this invention is has been found that by incorporating in a suitable mineral oil base an additive combination comprising an oil-soluble barium salt of an engines, which will give in fuel combinations for use in spark-ignited, Z-cycle, internal combustion engines, which ice alkyl phenol sulfide and an oil-soluble, alkaline earth metal sulfonate, both of which have ash-forming tendencies, there is produced a lubricant which may be employed in the formulation of an oil-fuel mixture for use in Z-cycle engines which will not form excessive combustion chamber deposits or produce preignition during the operation of the engine. To efiect the objectives of the invention, in the formulation of the 2-cycle engine lubricant of this invention, it is necessary to incorporate into one or both of these additive constituents a reserve alkalinity sutficient to provide a finished oil having a Total Base Number (ASTM Designation: D 664-54) within specific ranges.

The oil-soluble, barium salts of alkyl phenol sulfides employed in this invention are those products which are derived by converting an alkyl phenol sulfide into the barium salt by neutralization with barium hydroxide. The alkyl substituent groups, R, contain 4-21 carbon atoms to effect improved oil solubility. The sulfide linkage, (S) connecting the phenolic nuclei can be mono-, di-, or polysulfide. These compounds are well known in the art and are comprehensively discussed in US. Patents 2,249,626, 2,289,795, 2,294,145, 2,335,017, 2,-

336,074, 2,362,291, 2,399,877, 2,399,878, 2,409,687, et al;

O-Ba 0 Maximum basicity is provided by neutralizing with at least 2 mols of barium hydroxide per mol of alkyl phenol sulfide to produce a basic barium salt having the structural formula:

Obviously, intermediate basicities can be produced by varying the amount of barium hydroxide employed in the neutralization of the alkyl phenol sulfide. Examples of suitable salts include but are not limited to the barium salts of tertiary-octyl phenol sulfide; di-tertiary-amyl phenol sulfide; di-2,4-diamyl phenol sulfide; dibutyl phenol sulfide; dicetyl phenol sulfide, etc.

The amount of barium salt of an alkyl phenol sulfide employed will depend upon its basicity, the proportion of reserve alkalinity which the salt is to contribute to the finished oil. Generally this will vary between 05-30% by weight, based on the mineral oil base. While 1-2.5 Wt. percent is preferred, amounts outside this range may be necessary to provide the necessary reserve alkalinity.

The other ash-forming constitutent of the composite additive is selected from the oil-soluble, alkaline earth metal sulfonates. These include the salts of petroleum sulfonic acids as well as the synthetic sulfonates. The sulfonic acids which are converted to the selected alkaline earth salt are derived from the sulfonation of petroleum oil fractions, such as lubricating oil distillates, with fuming sulfuric acid, chlorosulfonic acid, sulfur trioxide, etc., to produce high molecular weight (400-600), oil-soluble, so-called mahogany sulfonic acids; or the sulfonation of an aromatic nucleus which has been alkylated with a paraffin wax chain having 20 or more carbon atoms, e.g., wax-substituted naphthalene sulfonic acids. Although it is preferred that neutral alkaline earth metal sulfonates be employed and any reserve alkalinity in the finished lubricating oil be provided by the barium salt of an alkyl phenol sulfide, basic sulfonates can be prepared in accordance with conventional techniques and be utilized for this purpose. Sulfonates which can be employed in formulating the composite additive of this invention include calcium petroleum sulfonate, barium petroleum sulfonate, basic barium wax-substituted naphthalene, etc. It is preferred that the oil-soluble petroleum sulfonates be employed.

The amount of oil-soluble sulfonate which is employed will, as in the instance of the barium phenol sulfide, depend upon the amount of reserve alkalinity contributed by this portion of the composite additive functioning to provide this characteristic in the finished oil. Generally 0.25 to 1% by Weight, based on the mineral oil base will sufiice; however, it may be necessary in carrying out the teachings of this invention to use amounts outside this range.

In order to effectuate the results of this invention, it it necessary that both the barium alkyl phenol sulfide and alkaline earth sulfonate be employed regardless of whether all the reserve alkalinity is provided by just one of the constituents. Accordingly, at least 1 part of sulfonate per 10 parts of sulfide should be used. It is preferred that the barium phenol sulfide be employed in the major amount, using a ratio of barium phenol sulfide to alkaline earth metal sulfonate of about l l:l.

The lubricating oil base employed in this invention may be refined mineral oil distillate, or a blend containing bright stock and a neutral fraction. In this particular service, parafiinic lubricating oil is preferred as the base oil because of inherent cleanliness and low carbon residue. However, other base oils, such as Mid-Continent, East Texas, etc., which have been adequately refined by solvent treatment to produce a lubricating oil base having substantially the same characteristics as a paralfinic oil, can be used. Satisfactory lubricants for use in formualkalinity. However, available lubricating oil base stocks may not have satisfactory temperature-viscosity characteristics. If an improvement in these properties is required, it may be effected by the addition of conventional V.I. improvers well known in the art. Suitable examples include the polymers of the esters of methacrylic acid and the higher fatty alcohols, such as cetyl, lauryl, octyl, etc., having a molecular weight of l0,000-20,000. Commercial copolymers of this type are sold by Rohm & Haas, e.g., Acryloid 618, 710, 763, 788, 794. Other compounds which function in this manner are the butene polymers having a controlled molecular weight of 10,000l5,000. This composition is marketed by Enjay Company, Inc., under the mark Paratones. Another well-known commercial product is Santodex sold by Monsanto Chemical Company. This compound is a high molecular weight alkyl styrene polymer and may be considered as a copolymer of styrene and C C olefins. The foregoing are typical products which can be employed as viscosity index improvers. However, other similar compositions may be employed. The amount of this constituent employed Will depend upon the degree of improvement desired. Generally, I to 5% by Weight based on finished com osition will produce satisfactory results.

To illustrate the instant invention, a number of lubricating oil blends were tested in an O.B.C. certified H. P. Scott Atwater 2-cycle marine engine of the outboard type. The oils tested contained a variety of conventional proprietary detergents and included an additive-free lubricating oil. This engine was mounted in a stationary test stand in a water bath to simulate actual operating conditions. A lubricant-fuel mixture of one-half pint of lubricant per gallon of gasoline was used. The gasoline contained 3 cc. of tetraethyl lead. The tests were run under the following conditions:

l) 25 hours at full throttle (2) 4200 rpm. at full throttle (3) No idle periods (4) Cooling water temperature-80 F. (5) Engine cooling water dischargel00-120 F.

In Table I are shown the unsatisfactory results obtained for a variety of lubricating oils employed in the 45 lubricant-fuel mixture used in the test.

TABLE I Efiect of lubricating oil on spark plug fouling,

pre-igni- Lubricating Oil A B O D E F G ASTM Test Designation Gravity, A.P.I

Flash (D 92-46) (D 92-46) (D 445-531) (D 445-531" (D 567-53) (D 97-47) or D 189-46) Neutralization Value (Total Acid Num- (D 974 54T) ber Percent Carbon Residue (D 139 52) Percent Sulfur (D 129 52) Ash Analysis (D 81148) Percent Ash as S04... 1) g74 Percent Ash as Oxide."

Percent Phosphorus (D 1091 54T) Detergent Additive, percent Test Results (Engine Performance) Preig'nition Cleanliness Poor Spark Plug Failure Failurem. Failure Failure Fai1ure lating lubricant-motor fuel admixtures for the operation of 2-cycle, spark-ignited, internal combustion engines can be prepared, employing a composition consisting essentially of a proper oil-soluble combination of a barium phenol sulfide and an alkaline earth metal sulfonate in a lubricating oil base to provide the necessary reserve However, when the combination detergent additive, of this invention, is barium alkyl phenol sulfide-alkali metal sulfonate having reserve alkalinity properties sufiicient to impart to the lubricant, employed in the lubricant-fuel mixture under the above test conditions, a Neutralization Value (Total Base Number) of 0.6 to 3.5, spark plug the Acryloid series,"

fouling and preignition were eliminated and a substantial improvement in engine cleanliness, especially in the engine manifold, was produced. These results and the critical effect of reserve alkalinity is shown in Table II.

TABLE II Composition 1 2 3 High V.I. Bright Stock Lubricating Oil (150 S.U.S. at 2l0 F./ 95 V.I.).

Intermediate V.I. Bright Stock Lubricating Oil 1 (160 S.U.S. at 210 F./95 V.I.).

170 Vis. Neutral Lubricating Oil X (170 S.U.S. at 100 F.I95 V.I.).

200 Vis. Neutral Lubricating Oil 1 (200 S.U.S. at 100 F./95 V.I.).

Barium tertiary octyl phenol sul' e. Calcium petroleum sulionate Viscosity Index lrnprover 4 Characteristics 5 Gravity Flash Fire- Viscosity, S.U.S. at:

Color Neutralization Value (Total Base Number).

Carbon Residue, Percent-.-"

Sulfur, Percent Ash Analysis Ca, 321....

Percent Ash as 804.- 0.68 1 08 Percent Ash as Oxide Test Results (Engine Performance):

Preignition Excellent Border line- Poor.

Engine Cleanlm' ess- Excellent- Excellent..- Eilrcelt- Spark Plug Failure No Yes Yes.

1 Oils derived from the refining of Mid-Continent lubricating stock by phenol extracting, MEK dewaxing, and contact filtration.

I A barium tertiary octyl phenol sulfide having the following characteristics:

Total Acid Total Base Sulfur, Suliated Residue No. No. Wt.

(D 6364-54) (D 664-54) Percent I A substantially neutral oilsoluble sulfonate derived from the sulfonation of a Mid-Continent solvent refined lubricating oil fraction.

4 A proprietary V.I. improver-Acryloid. 7l0-comprising a oopolymeric mixture of the esters of methacrylic acid and lauryl and octyl alcohols in a high quality solvent refined neutral lubricating oil.

1 Characteristics determined in accordance with the ASTM test procedures set forth in Table I.

It will be noted that in the tabulated formulations volume percentages of ingredients were employed. This is in accordance with standard petroleum refinery blending procedures. In employing the combination additive of this invention, it should be dispersed in a light mineral oil to facilitate handling and blending.

In testing lubricating oil containing barium phenol sulfide-alkaline earth metal sulfonates in lubricant-fuel mixtures, it was found that lubricating oils having a Neutralization Value of less than 0.6 (Total Base No.) were unsatisfactory. Also lubricating oils having Neutralization Values of greater than 3.5 (Total Base No.) caused preignition and plug failures. Accordingly, the subject invention is directed to the formulation of lubricating oils having a reserve alkalinity within this range for use in compounding lubricant-fuel mixtures employed in the operation of 2-cycle, internal combustion engines. It has been found that by employing a combination additive comprising a barium phenol sulfide and an alkaline earth metal sulfonate wherein either or both of the constituents have a Neutralization Value (Total Base No.) sufiicient to impart to the finished oil a Neutralization Value (Total Base No.) within the desired range, excellent engine cleanliness of the combustion chambers, piston skirts, ring grooves, exhaust parts over extended periods is obtained without concomitantly producing preignition and spark plug failures.

Because of the unique deposit flaking and other properties of this additive combination, the formulation of multi-graded Z-cycle motor lubricants which may be used in engines operated over a wide atmospheric temperature range, and may contain deposit-forming bright stocks of high carbon residue, is permitted.

In order to obtain satisfactory performance in the operation of the 2-cycle engines using conventional lubricants, it is necessary that the gasoline motor fuel employed not have a high content of tetraethyl lead, and it is recommended that the gasoline used contain not more than /2-1 cc. of T .E.L. per gallon. However, by employing the lubricant of this invention in the formulation of a lubricant-fuel admixture up to about 3 cc. of T.E.L. per gallon can satisfactorily be employed with accompanying advantages. The gasoline motor fuels are standard grades and may contain straight run distillates as well as cracked fractions. These gasolines may be produced in conventional petroleum refining operations. The ratio of oil to gasoline motor fuel varies according to the recommendations of engine manufacturers. In general, the amount of oil employed will vary between /3 pint and 2 pints per gallon of gasoline. However, amounts outside these ranges can be employed. In employing the instant invention in the operation of Z-cycle, spark-ignited, internal combustion engines, maximum performance can be obtained where a mineral oil base having a multi-grade feature is used in the fornation of the lubricant; one oil can be used in all applications where various engine manufacturers recommend S.A.E. grades of oil within the graded range.

We claim as our invention:

1. A method for operating a spark-ignited, 2cycle, internal combustion engine, which comprises introducing into the combustion chamber of said engine, a combustible admixture of air and a fuel consisting essentially of a major portion of a gasoline, and a minor portion of a lubricant consisting essentially of the following three components: (1) a major portion of a mineral lubricating oil having enhanced viscosity-index characteristics, (2) 1.0 to 2.5 wt. percent, based on said oil, of a barium salt of an alkyl phenol sulfide, and (3) 0.25 to 1.0 Wt.

- percent, based on said oil, of an oil soluble alkaline earth metal sulfonate, at least one of the components 2 and 3 having a Neutralization Value (Total Base Number) to impart to said oil, when added thereto in the aforesaid amount, a Neutralization Value (Total Base Number) of 0.6 to 3.5.

2. A method in accordance with claim 1 in which said fuel consists of about /3 to 2 pints of lubricant per gallon of gasoline.

3. A method in accordance with claim 2 in which said gasoline contains not more than 3 cc. of anti-knock agent per gallon of gasoline.

4. A lubricant for 2-cycle, internal combustion engines employing a fuel comprising a lubricant-gasoline mixture, said lubricant consisting essentially of the following three components: (l) a major portion of a mineral oil base having enhanced viscosity index characteristics, (2) 0.5 to 3.0 wt. percent of a barium salt of an alkyl phenol sulfide, and (3) 0.25 to 1.0 wt. percent of an oil-soluble alkaline earth metal sulfonate, wherein at least one of the components 2 and 3 has a Neutralization Value (Total Base Number) which will, when added to said oil in the aforesaid amount, impart to said oil, a Neutralization Value (Total Base Number) of 0.6 to 3.5.

5. A lubricant in accordance with claim 4 in which said sulfide is barium di- (tertiary-octyl phenol) sulfide.

6. A lubricant in accordance with claim 5 in which said sulfonate is calcium petroleum sulfonate.

7. A composition in accordance with claim 6 in which said sulfide has a Neutralization Value (Total Base Number) of about 77 and is present in the amount of 1.9 percent by wt. of the oil, and said sulfonate is substantially neutral.

8. A lubricant-gasoline mixture for 2-cycle internal combustion engines employing a fuel comprising said lubricant-gasoline mixture, said mixture consisting essentially of a major portion of a gasoline motor fuel and a minor portion of a lubricant consisting essentially of the following three components: (1) a major portion of a mineral lubricating oil having enhanced viscosityindex characteristics, (2) 0.5 to 3.0 wt. percent based on v the lubricating oil, of a barium salt of an alkyl phenol sulfide, and (3) 0.25 to 1.0 Wt. percent, based on the lubricating oil, of an oil-soluble alkaline earth metal sulfonate, wherein at least one of the components 2 and 3 has a Neutralization Value (Total Base Number) which will, when added in the aforesaid amount to said oil, impart thereto a Neutralization Value (Total Base Number) of 0.6 to 3.5.

claim 9 in which said gasoline contains not more than 3 cc. of anti-knock agent per gallon of gasoline.

References Cited in the file of this patent UNITED STATES PATENTS 1,489,763 Jacobs Apr. 8, 1924 1,682,561 Hennen Aug. 28, 1928 2,409,687 Rogers Oct. 22, 1946 2,744,083 Moody May 1, 1956 2,761,845 Rogers Sept. 4, 1956 2,779,784 Sharrah Jan. 29, 1957 2,794,829 Van der Waarden June 4, 1957 

1. A METHOD FOR OPERATING A SPARK-IGNITED, 2-CYCLE, INTERNAL COMBUSTION ENGINE, WHICH COMPRISES INTRODUCING INTO THE COMBUSTION CHAMBER OF SAID ENGINE, A COMBUSTIBLE ADMIXTURE OF AIR AND A FUEL CONSISTING ESSENTIALLY OF A MAJOR PORTION OF A GASOLINE, AAND A MINOR PORTION OF A LUBRICANT CONSISTING ESSENTIALLY OF THE FOLLOWING THREE COMPONENTS: (1) A MAJOR PORTION OF A MINERAL LIBRICATING OIL HAVING ENHANCED VISCOSITY-INDEX CHARACTERISTICS, (2) 1.0 TO 2.5 WT. PERCENT, BASED ON SAID OIL , OF A BARIUM SALT OF AN ALKYL PHENOL SULFIDE, AND (3) 0.25 TO 1.0 WT. PERCENT, BASED ON SAID OIL, OF AN OIL SOLUBLE ALKALINE EARTH METAL SULFONATE, AT LEAST ONE OF THE COMPONENTS 3 AND 3 HAVING A NEUTRALIZATION VALUE (TOTAL BASE NUMBER) TO IMPART TO SAID OIL, WHEN ADDED THERETO IN THE AFORESAID AMOUNT, A NEUTRALIZATION VALUE (TOTAL BASE NUMBER) OF 0.6 TO 3.5. 